NorthFinder

The Challenge:

Evolutionary improvements in the performance of weapon delivery systems have outpaced Far Target Location (FTL) capabilities, resulting in the undesirable outcome to “precisely miss the target” at long standoff distances.

Over the past two decades, Applied Technology Associates (ATA) has refined a pioneering Angular Rate Sensor (ARS), which is based on Magnetohydrodynamic (MHD) principles, and combined it with other aiding sensors, electronics, and algorithms to develop an MHD-based NorthFinder. For information on our recent success
click here.

Magneto-Hydrodynamic NorthFinding Principle

Basic Principle of Operation:

The fundamental approach involves precisely measuring the orientation of the earth’s “spin” vector (i.e. North). The key enabler is ATA’s MHD ARS which is insensitive to bias errors and has strategic grade noise performance which results in rapid Northfinding.

By rotating the ARS, it detects the in-plane component of Earth rate, thus, creating a sinusoidal signal whose phase encodes the angle between Earth rate and the sensor. This approach diverts the emphasis from bias stability to that of noise level over a narrow spectral band. The innovative use of symmetry provides inherent error cancellation.

In April 2009, under IR&D funding, ATA established the first reduction to practice of a proof-of-concept all-inertial NorthFinder (NF) based on a magnetohydrodynamic (MHD) gyro. Leveraging (Army and Navy) SBIR sponsorship, the technology rapidly matured giving rise to the lab-tested M2 and field demonstrated M3 Northfinding devices. Both the M2 and M3 devices demonstrated sub 2 mrad azimuth determination during indoor testing. In August 2010 the M3 device further established the viability of this technology during field testing at Quantico, VA by demonstrating sub 4 mrad azimuth determination in less than 60 seconds which was subsequently transitioned to less than 30 seconds. The figure below illustrates the chronological evolution of ATA’s NorthFinder solution into a full PAVAM solution noting the major milestones to date.

Ongoing Spiral Development:

ATA employed a spiral development process to rapidly mature the NorthFinding technology. Beginning with the Proof of Concept (POC) pathfinder which led to the development of the M2 and M3 performance demonstrator systems. This evolutionary progression led into the fully self-contained Earth Referenced Attitude Detector Technology Demonstrator (ERAD-TD).